Where should my fuel pressure be?

[Heybluez]

It seemed to be on the low side when I started flying today. It picked up a little later on but definitely sits towards the left side. This normal/ok?

P.S. 1 week of Mooney ownership. I love this plane!

[Danb]

Just take a quick spin over to Klns and ask Dorn at Webers to show you how/where the knob is...a nice little flight from Kpne where I think your based...good luck..

[MooneyBob]

It seemed to be on the low side when I started flying today. It picked up a little later on but definitely sits towards the left side. This normal/ok?

P.S. 1 week of Mooney ownership. I love this plane!

Seems low. My is around 22 in my J.

[Marauder]

It seemed to be on the low side when I started flying today. It picked up a little later on but definitely sits towards the left side. This normal/ok?

P.S. 1 week of Mooney ownership. I love this plane!

That pressure is on the low side. My F shows 24 to 25 on both the EI FP-5L and the JPI 900.

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[N601RX]

My F runs around 25. Try flipping on the boost on and see if it rises.

[jetdriven]

Yep as 601rx says, turn on the boost pump it should be around 25-30. If not it could be an indication issue. Usually I see 20-25 psi. Perhaps a little less on takeoff. Lycoming swears that 13 PSI is totally normal but it runs leaner there.

[Bob_Belville]

I see 22-24, a little higher at idle. JPI 930.

[Marauder]

Yep as 601rx says, turn on the boost pump it should be around 25-30. If not it could be an indication issue. Usually I see 20-25 psi. Perhaps a little less on takeoff. Lycoming swears that 13 PSI is totally normal but it runs leaner there.

With my boost pump on, I'm at 27 psi on both devices.

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[Ftlausa]

In my J it runs near the top of the green. 

[ArtVandelay]

In my J it runs near the top of the green.

My J runs near the bottom of green. My OP run below the green, JPI indicates correct pressure. Also the gauges have a small variation, rhythmic like it has s pulse. Someday I'll need to have them overhauled.

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[Heybluez]

So should I have an a&p check it out? I do notice that I tend to have to turn on boost pump as I turn the key on start up. Even after turning the pump on and off for five seconds as the check list suggests. Could my pump be going bad? It just I don't know how to start my plane?!

[Marauder]

So should I have an a&p check it out? I do notice that I tend to have to turn on boost pump as I turn the key on start up. Even after turning the pump on and off for five seconds as the check list suggests. Could my pump be going bad? It just I don't know how to start my plane?!

On my IO-360, the cold start is throttle cracked, mixture full rich, boost pump on, mixture idle, boost pump off, start, enrich mixture.

Never needed to use the boost pump during the starting process. Are you saying you need to use it or did you just pick up a bad habit? The plane should start as per the cold start procedure in your POH/AFM.

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[Piloto]

Low pressure is sometimes related to a leak on the engine pump diaphragm. To check for this:

On the ground with engine off set throttle and mixture forward. Turn the electric pump on and let pressure build up. With the pump running close throttle and mixture. Turn the pump off. The fuel pressure should hold for at least five minutes. If the pressure drops after turning the pump off there is leak in the system or the fuel pump. Check the engine fuel pump breather line. Fuel coming out of it is an indication of a leaky diaphragm.

José

[carusoam]

+1 for Josés explanation.

Priming an engine takes experience.

The experience takes a number of times to acquire.

The experience gets adjusted for OAT and CHT.

Then the pump leaks.

My engine has two pump settings, three procedures and one thing to avoid...

The one thing...priming properly requires the throttle open...

The engine usually fires up within a few rotations of the prop.

Best regards,

-a-

[Bob_Belville]

On my IO-360, the cold start is throttle cracked, mixture full rich, boost pump on, mixture idle, boost pump off, start, enrich mixture.

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I would tweak that slightly: run the fuel pump with both throttle and mixture full forward. Then pull both back: mixture to cutoff; throttle to ~ 1000 rpm position, wait a few seconds  and engage starter. Advance mixture after the engine fires. (If the "cracked" throttle is open enough it probably does make a difference.)

[Guest]

Think of starting a 152/172 during primary flight training. Throttle cracked, mixture rich, a few strokes of the primer, primer locked, hand on throttle turn key and enjoy.

Starting your fuel injected Mooney is basically the same, throttle full open, mixture full rich, fuel boost pump on for a few seconds then off, throttle closed, then cracked open, hand on throttle, turn key and enjoy.

All engines require fuel, air and sparks in the correct ratios for operation.

Clarence

[Heybluez]

Update. The mechanic hooked it up to a pressure gauge and the pressure is 2-4 lbs more than what the gauge is showing. He is going to look at the transducer to determine if it is that or the gauge. He said he was looking at the manual for the voltages?

Ok, question, does that sound right to you guys? What can I tell him to look at?

Thanks!

MJP

[Bill_Pyles]

My needle position looks the same as the one in your photo.  I had Top Gun in Stockton, CA test the pressure in my J and they said my gage read abouot 2-3 needle widths low, and that my actual pressure was "normal."

[Heybluez]

Thanks Bill, good to know. I'm thinking mine is "normal" too just don't like the gage not being accurate. I'll let you know what I dig up. Best, MJP

[Heybluez]

UPDATE -- after weeks work on this, that story another time , it turns out the A&P calibrated the fuel pressure gage to what the fuel pressure was. Everything else was functioning as it is supposed to. Now it reads at 25 pretty consistently.  There are apparently two screws that allow you to calibrate it.  

 

Best,
MJP